The present invention relates to a display device, and more particularly, to a liquid crystal display device with a high definition screen in a lateral electric field mode that prevents the occurrence of a domain.
A liquid crystal display device includes a TFT substrate in which pixels having pixel electrodes, thin film transistors (TFT) and the like are formed in a matrix, as well as a counter substrate in which color filters and the like are formed at the positions corresponding to the pixel electrodes of the TFT substrate. The counter substrate is disposed opposite the TFT substrate with a liquid crystal interposed between the TFT substrate and the counter substrate. Then, the transmittance of light caused by liquid crystal molecules is controlled at every pixel to form images.
Liquid crystal display devices are flat and lightweight and have been applied in various fields. Small liquid crystal display devices are widely used in mobile phones, digital still cameras (DSC), or other portable devices. The viewing angle property is a problem for the liquid crystal display device. The viewing angle property is a phenomenon that the brightness or the chromaticity varies when the screen is viewed from the front and from an oblique angle. The viewing angle property is excellent in the in-plane switching (IPS) mode for operating the liquid crystal molecules by the electric field in the parallel direction.
There are various types in the IPS mode. Japanese Unexamined Patent Application Publication No. 2004-302448 describes a structure of an IPS mode liquid crystal display device with pixel and counter electrodes having a comb-like shape, in which an organic insulating film is formed on video signal lines in order to reduce the parasitic capacitance between the video signal lines and the upper electrode (which may be the pixel electrode or may be the counter electrode).
Japanese Unexamined Patent Application Publication No. Hei 09(1997)-105918 describes, for example, a method for forming a common electrode in a matted manner, disposing a comb-like pixel electrode on the common electrode with an insulating film interposed therebetween, and rotating liquid crystal molecules by an electric field generated between the pixel electrode and the common electrode. This method has the property of being able to increase the transmittance.